Phytotaxa 348 (1): 056–062 ISSN 1179-3155 (print edition) http://www.mapress.com/j/pt/ PHYTOTAXA Copyright © 2018 Magnolia Press Article ISSN 1179-3163 (online edition) https://doi.org/10.11646/phytotaxa.348.1.7 Pachyphytum rogeliocardenasii (Crassulaceae), a new species from northwestern Querétaro, Mexico EMMANUEL PÉREZ-CALIX1* & RAFAEL TORRES-COLÍN2 1Instituto de Ecología, A.C., Centro Regional del Bajío, Av. Lázaro Cárdenas 253, Col. Centro, Pátzcuaro, Michoacán, México. C. P. 61600. 2 Universidad Nacional Autónoma de México, Instituto de Biología, Departamento de Botánica, Herbario Nacional (MEXU), Apartado postal 70-367, 04510 Cd. México, México. *Author for correspondence: [email protected] Abstract Pachyphytum (Crassulaceae) is a genus of perennial plants with ca. 20 species endemic to central Mexico. Pachyphytum rogeliocardenasii is described here as a new species. It is compared to P. garciae, which is morphologically similar. The new species is endemic to the northwestern region of the state of Querétaro where it was found on limestone walls. It is assigned the category of endangered (EN). Key Words: Arroyo Seco, sect. Diostostemon, sect. Ixiocaulon Resumen Pachyphytum (Crassulaceae) es un género de plantas perennes que contiene ca. 20 especies endémicas del centro de México. Aquí se describe a P. rogeliocardenasii como especie nueva para la ciencia. Se compara con P. garciae con la que morfológi- camente parece estar relacionada. La nueva especie es endémica de la región noroeste del Estado de Querétaro; habita en paredes de roca caliza; se le asigna en la categoría de En Peligro (EN). Palabras Clave: Arroyo Seco secc. Diostostemon, secc. Ixiocaulon Introduction Pachyphytum Link, Klotzsch & Otto (Klotzsch, 1841: 9) is a genus of the family Crassulaceae, comprising perennial or suffrutex herbs, generally pendant; leaves close to the stem apex, or sometimes forming a lax rosette; the blades are succulent and vary from flat and thick to terete; its inflorescence is a bracteate cincinnus; showy flowers, gamosepalous calyx, equal or unequal lobes, longer or the same size as the petals; gamopetalous corolla, each petal has two marginal appendages on the inner side (Thiede 2003, Pérez-Calix 2008). Systematic studies reveal that Pachyphytum is related to Echeveria De Candolle (1828: 401), based on morphological evidence (Berger 1930, Moran 1963, 1965, 1968, Walther 1972, Thiede 2003), as well as molecular phylogenetic studies of Crassulaceae (Ham & Hart 1995, Carrillo-Reyes et al. 2009). Morphologically, the plants assigned to Pachyphytum are different from those grouped in Echeveria, which have a pair of appendages (scales) on the inner surface of each petal that are considered folds of the margins of the petals (Leinfellner 1954). Additionally, the petals of Echeveria are imbricated at the base, whereas in Pachyphytum they are imbricated in the apical portion, at least in bud, but not during anthesis, and narrow in the middle (Walther 1931, Moran 1965). According to Moran (1968, 1971), Pachyphytum is subdivided into three sections based on morphological characters: Diostostemon Salm-Dyck (1854: 265) Walther (1931), Ixiocaulon Moran (1968: 41), and Pachyphytum Moran (1968: 39). Thiede (2003) only recognizes the first and third sections. The genus Pachyphytum comprises ca. 20 species, endemic to central Mexico, from southern Tamaulipas to San Luis Potosí, Guanajuato, Querétaro, Hidalgo, and Michoacán, as well as to the Central-Western region, up to northern Jalisco. They grow mainly on rocks (Pérez- 56 Accepted by Nicodemo Passalacqua: 23 Mar. 2018; published: 24 Apr. 2018 Licensed under a Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0 Calix 2008). For the state of Querétaro, Pérez-Calix (2008) reports Pachyphytum compactum Rose (1911: 301), P. garciae Pérez-Calix & Glass (1999: 4), P. glutinicaule Moran (1963: 37) and P. viride Walther (1937: 210). In an exploration carried out by the second author in the northwest region of the state of Querétaro, Mexico, a species of Pachyphytum was collected that could not be identified with the specialized literature in the group (Meyrán & Chávez 2003, Thiede 2003, Pérez-Calix 2008). Hence, it is described here as a new species to science. It is compared with P. garciae, to which it is morphologically similar, and its conservation status is proposed. Material & Methods The Santa María de Cocos region and adjacent canyons, where the population of the new Pachyphytum species was collected, were explored with the objective of collecting samples to document the morphological variation of the species, its phenology and habitat, as well as looking for additional populations. The morphological description of the species was prepared based on collections from the field. Because the plants are succulent, the process of herborization alters the shape and size of their organs. To avoid this problem the data were taken from living organisms, which were later herborized and deposited in the herbaria IEB, MEXU, and QMEX. Observations of small structures were performed using a Leica M80 stereo microscope. The conservation status of the species was determined on the basis of the criteria of the IUCN (2012). Taxonomy Pachyphytum rogeliocardenasii E. Pérez-Calix & R.Torres, sp. nov., Fig. 1; Fig. 2 A‒D. Type:—MEXICO. Querétaro: municipio Arroyo Seco, cerca de 2.9 km al sur de Santa María de Cocos, 800 m elevation, 21°18’24.64” N, 99°38’26.54” O, 3 November 2015, E. Pérez 6616 (holotype IEB!, isotypes MEXU!, QMEX!). Pachyphytum rogeliocardenasii is morphologically similar to P. garciae, which differs in that its leaves are up to 1.3 cm longer and 0.5 cm wider; the bracts of the peduncle are 6‒7.5 mm longer and 2‒3.5 wider; calyx lobes are also larger and corolla lobes are white with an abaxial red spot in the middle. Suffrutex herb, succulent, pendant, decumbent, glaucous, glabrous; stems often unbranched or branched from near the base, 60 cm long or less, up to 0.6 cm thick. Leaves sessile, arranged in a spiral at the apex of the stem, in lax rosettes, laminas narrowly to widely elliptic or obovate, (2.5‒)3.2‒5.8 cm long, (1.5‒)1.8‒2.8 cm wide, (0.4‒)0.6‒10 mm thick, transversely elliptic in cross-section, apex rounded or obtuse, margin entire, succulent, green, slightly pruinose, glabrous. Inflorescence axillary, near the apex of the branches; peduncle 9‒23 cm long until the first flower, pink, pruinose; bracts elliptical to oblong-elliptical, 12‒18 mm × 6‒10 mm, obtuse at the apex, cuneate-attenuate at the base, flat, green, pink with age; flower bracts subimbricate in young cincinnus, ovate, obovate, oblong, elliptical, to oblong- elliptical, 8.5‒16 mm × 5‒9 mm. Flowers on a turbinate pedicel, 3‒7 mm × 1.5‒2 mm, pruinose. Calix 5-lobate, lobes unequal, the largest oblong, 9.5‒13 mm × 4.2‒6 mm; the smaller oblong, 8‒10 mm × 2.5‒3.5 mm, apex acute, mucronate. Corolla gamopetalous, 5-lobate, lobes oblong, 7‒9 mm × 2.5‒3 mm, apex acute, yellowish-white with an abaxial red spot in the middle; scales red. Stamens 10, 5 antipetalous, 2.5‒4 mm long, 5 antisepalous, 5‒6.5 mm long. Nectaries narrow, transversely elliptical, ca. 0.5 mm long, yellowish. Ovary ca. 6 mm, style ca. 2 mm long. The fruit a follicle, ca. 8 mm long, seeds numerous, narrowly obovoid. Distribution and habitat:—Pachyphytum rogeliocardenasii is endemic to the northwest region of Queretaro, near the border with Guanajuato where one population that lives on vertical walls of limestone sedimentary rock has been recorded in the canyon of the Atarjea river. The climate of the region is subhumid, semi-warm (sensu García 1973). The vegetation corresponds to the deciduous tropical forest (sensu Zamudio et al. 1992). Some of its elements are Celtis iguanaea and various representatives of Leguminosae. The walls where the plant grows are also habitat by populations of Agave sp., Hechtia sp., Echeveria sp. and Sedum corynephyllum. Additional material examined (paratypes):—MEXICO. Querétaro: municipio Arroyo Seco, Cañon de Atarjea, sobre paredes en el lecho del río, 3 km al SW de Santa María de Cocos, 800 m elevation, 21°18’24.64” N, 99°38’26.54” O, 24 May 2015, R. Torres C. 17902, A. Zaldívar & V. Salinas (IEB!, MEXU!, QMEX!); cerca de 2.9 km al SW de Santa María de Cocos, 800 m elevation, 21°18’24.64” N, 99°38’26.54” O, 16 June 2015, E. Pérez 6605 (IEB!). Phenology:—The new species is suffrutex and perennial, so it can be seen with the leaves arranged near the apex of the hanging stems throughout the year. It has been registered flowering in November and eventually in June. PACHYPHYTUM ROGELIOCARDENASII Phytotaxa 348 (1) © 2018 Magnolia Press • 57 FIGURE 1. Pachyphytum rogeliocardenasii E. Pérez-Calix & R. Torres, sp. nov. A) Habit; B) Variation of the foliar lamina and cross section of the leaf blade; C) Cincinnus lateral view; D) Cincinnus adaxial view; E) Flower; F) Flower dissection; G1) Petal abaxial view; G2) Petal lateral view; H) Seed. (A‒H based on E. Pérez 6616, IEB) Conservation status:—Pachyphytum rogeliocardenasii is assigned in the category of Endangered, based on the proposal of the International Union for Conservation of Nature, under the Criterion B, sub-criteria 1a and 2a; and Criterion C, sub-criteria 2a (EN B1a+2a; C2a) (IUCN, 2012). It is estimated that the only known population has less than 1000 mature individuals and its area of occupation is very small (ca. 150 m2). Etymology:—The specific epithet is dedicated to the memory of Rogelio Mariano Cárdenas-Soriano (Cuautla, Morelos, 1961 - Pátzcuaro, Michoacán, 2010). Rogelio worked as a scientific illustrator in the Bajío Regional Center of the Institute of Ecology, A.C., from 1995 until his death, and elaborated a series of illustrations, published in the fascicles of Flora del Bajío and of adjacent regions; he also drew new taxa for science, which were published in various specialized journals in botany.